Molecular beam source for use of thin-film accumulation and a method for controlling volume of molecular beam

ABSTRACT

A molecular beam source for use of thin-film accumulation, for enabling to adjust the volume of molecular beam, which is discharged per an hour with using a needle valve, to be constant irrespective of decrease of a thin-film element forming material remaining within a crucible, comprises heaters  32  and  42  for heating the thin-film element forming materials “a” and “b” within crucibles  31  and  41 , and valves  33  and  43  for adjusting the volumes to be discharged of molecules of the thin-film element forming materials “a” and “b”, which are generated within the crucibles  31  and  41 . And, it further comprises a control means for adjusting openings of the valves  33  and  43  by means of servomotors  36  and  46  through feeding back of information relating to the volumes of molecular beams, which are obtained from film-thickness meters  16  and  26  for detecting the volume of molecular beams discharged towards the film-forming surface, a heating electric power source for supplying an electric power for heating the heaters  32  and  42 , and a control means for adjusting an electric power to be supplied to the heating electric power source depending upon the information relating to the volume of molecular sources and information relating to openings of the valves.

BACKGROUND OF THE INVENTION

The present invention relates to a molecular beam source for use of thin-film accumulation or deposition and a method for controlling an amount or volume of molecular beam, through heating a material to be formed on a film-forming surface of a solid body or matter, such as, a substrate, etc., in the form of a thin-film, by melting, sublimating or evaporating material(s) for forming a thin-film element; i.e., generating evaporated molecules for growing up the thin-film(s) upon the surface of the solid body, and it relates, in particular, to a molecular beam source for use in thin-film accumulation, being suitable for accumulating or depositing an organic thin-film upon a film-forming surface of the solid body, such as, the substrate, etc., continuously for a long time, and a method for controlling an amount or volume of the molecular beam therefrom.

A thin-film deposition apparatus, being called by a “molecular beam epitaxy apparatus”, comprises a decompressable vacuum chamber, into which the substrate, such as, the semiconductor wafer, etc., can be mounted under high vacuum condition, to be heated up to a desired temperature, while providing a molecule supply source cell, such as, the Knudsen cell, etc., for example, opposing to the film-forming surface thereof. Thus, a material for forming a thin-film element (hereinafter, a thin-film element forming material), which is put into within a crucible of the molecule supply source cell, is heated by means of a heater, to be sublimated, melted, or evaporated, so that a molecular beam generated thereby is incident upon the film-forming surface of the substrate; i.e., brining about the epitaxial growth of the molecules of the thin-film element forming material on the film-forming surface, thereby forming a film of the thin-film element forming material.

Such a molecular beam source cell, to be applied in the thin-film deposition or accumulation apparatus, has a crucible made of a material, such as, PBN (Pyrolithic Boron Nitride), etc., for example, being highly stable, thermally as well as chemically, so as to receive the thin-film element forming material therein, and an electric heater provided, surrounding an outside of the crucible, so as to heat up the thin-film element forming material therein; i.e., generating the molecules thereof through sublimation, melting, or evaporation of the thin-film element forming material.

In recent years, attentions are paid upon an organic thin-film element, such as, an organic electroluminescence (EL) and/or an organic semiconductor, for example, representatively. Those thin-film elements can be obtained; i.e., the thin-film element forming material is heated up within the vacuum, so as to blast the vapor thereof upon the surface of the substrate, and then it is cooled down to be solidified and bonded thereon. In general, the following method is applied; i.e., the thin-film element forming material is put into the crucible, which made of an inorganic material, such as, PBN, etc., or a material having the high melting-point, such as, tungsten, etc., and then the material to be formed as a film is heated through the heating by the heater provided around the crucible, thereby generating the vapor thereof to be blasted onto the substrate.

The organic electroluminescence (EL) , being as one representative example of such the organic thin-film element, is an element of forming a luminous layer from an organic low-molecular material or an organic high-molecular material, which has EL luminous ability, and attentions are paid upon, in particular, the characteristics thereof, i.e., as an element of self-luminous type. In the basic structures thereof, for example, on a film of hole transportation material, such as, triphenyl diamine (TPD) or the like, being formed on a hole injection electrode is laminated or deposited a fluorescent material, such as, aluminum-quinolinol complex (Alq₃), etc., as the luminous layer, and further thereon is formed an electrode of metal, having small work function, such as, Mg, Li, or Cs, etc., as an electron injection electrode. However, the materials of such the thin-film elements are expensive, in general.

By the way, when building up the thin-film elements, there is also necessity of time for exchanging the substrates, on the surfaces of which the thin film should be formed, and for adjusting the position of a mask for blasting the material only onto necessary portions thereof, etc. However, since many of the such the materials for the organic thin-film element as was mentioned above is sublimated or evaporated at relatively low temperature, the material is evaporated even during the time when exchanging of the substrates and/or aligning the position of the mask, etc.; i.e., there is a drawback that the very expensive material is wasted, uselessly.

Then, as is described in the following Patent Document 1, which will be mentioned below, there is proposed a molecule supply source for use in thin-film deposition of receiving the crucibles therein, each of which is hermetically sealed or closed in the structure, wherein a molecule discharge passage is provided for directing the molecules of the thin-film element material, which are generated within the crucibles, towards the film-forming surface, and further comprising a needle valve for adjusting an amount or volume of molecular supply on the way of the molecule discharge passage.

With the molecule supply source for use in thin-film deposition comprising such the valve mechanism, it is possible to cut or shut off the discharge of vapor of the material for the thin-film element, which is generated within the crucible, by means of the valve, and in addition thereto, to adjust the amount or volume of molecular supply by means of the needle valve, as well. For the purpose of forming the thin-film while maintaining a constant film-thickness and a quality thereof, it is effective to keep the volume of the molecular supply to be constant per an hour, which is discharged from the molecular supply source.

As the representative one of the material for organic thin-film elements mentioned above, there is already known the material of the EL thin-film element, and may of such the material for forming thin-film elements are in condition of granulated or powdered, and they are put into the crucibles in that conditions. Thus, with heating it received within the crucible by means of the heater, which is provided outside the crucible, the material of the EL thin-film element is heated and sublimated, and is evaporated to be discharged from towards the substrate, and thereby being deposited on the film-forming surface of the substrate for forming a film thereon.

When such the material of the EL thin-film element is sublimated and evaporated within the crucible to be discharged from, the volume is reduced, gradually, of the material of EL thin-film element remaining within the crucible. Then, since the surface area thereof is also reduced within the crucible, therefore the volume of sublimation of the material of EL thin-film element is also reduced, gradually, within the crucible. Accordingly, for the purpose of maintaining the volume of molecular supply discharged from the molecular supply source for use in deposition of thin-films, it is necessary to make an opening large of the needle valve, i.e., a ratio of the cross-section of the flow passage to that when the valve is fully opened, thereby to maintain the volume of molecular supply discharged from the molecular supply source for use in deposition of thin-films.

However, with the adjustment made on the volume of the molecular supply by means of the needle valve, it is finite or has a limit; i.e., when the needle valve is opened fully, then it is impossible to increase the volume of molecular supply, much more than that.

In the Patent Document 2 mentioned below, there are disclosed two (2) pieces of controller means, as the adjustment means for adjusting the volume of molecular supply. One of them is an adjustment means for adjusting the volume of molecular supply by means of the valve, as was mentioned above. The other one is a controller means depending on the temperature, at which the crucible is heated up by means of the heater. However, the controller means of the latter, depending on the temperature, at which the crucible is heated up by means of the heater, is not suitable for adjusting the volume of molecular supply, with accuracy, because control of the controller is in direct and has a time delay.

[Patent Document 1] Japanese Patent Laying-Open No. 2003-95787 (2003); and

[Patent Document 2] Japanese Patent Laying-Open No. Hei 6-80496 (1994).

BRIEF SUMMARY OF THE INVENTION

According to the present invention, being accomplished by taking the drawbacks of the conventional molecule supply source for use in thin-film deposition and the method for controlling the molecule supply thereof into the consideration, an object thereof is to provide a molecule supply source for use in thin-film deposition and also a method for controlling an amount of molecule supply, for enabling to adjust the volume of molecule supply to be constant per an hour, by means of the needle valve, irrespective of decrease in the remaining volume of the material for forming the thin-film elements within the crucible through discharge of molecules from the molecule supply source for use in thin-film deposition.

Thus, according to the present invention, there is provided a molecule beam source for use of accumulating a thin-film, for evaporating a material of thin-film element, comprising: a crucible for heating the material of thin-film element; a heater for heating said crucible; a molecule discharge passage for discharging molecules of the material of thin-film element generated within said crucible towards a film-forming surface; a vacuum container having hermetical sealed structure, for receiving said crucible, said heater and said molecule discharge passage therein; a valve for adjusting a volume of molecular beam discharged, being positioned on way of said molecule discharge passage; a detection means for detecting the volume of the molecular beam discharged towards said film-forming surface; a controller means for adjusting an opening of a valve by a valve driving means through feeding back information relating to the volume of the molecular beam detected by said detection means; a heating electric power source for supplying electric power for use of heating said heater; and a control means for adjusting the electric power to be supplied to said heating electric power source depending on said information relating to the volume of the molecular beam and valve opening information.

Also, according to the present invention, there is provided a method for controlling a volume of molecular beam, within a molecule beam source for use of accumulating a thin-film, for evaporating a material of thin-film element, comprising the following steps of: adjusting the electric power to the electric power source for heating said crucible if the valve opening necessary for obtaining a predetermined volume of molecular beam is equal to a predetermined reference value or larger than that, when evaporating an organic material upon a substrate, continuously; and thereby controlling the valve opening to fall within a range.

With the molecule beam source for use of accumulating the thin-film and the method for controlling the volume of molecular beam with using thereof, according to the present invention, as was mentioned above, while basing upon the control through the control means of volume of molecular beam, by means of the valve for enabling accurate control on the volume of molecular beam to be discharged, the volume of evaporation within the crucible per an hour is maintained by increasing temperature of the heater, when the material remaining within the crucible is consumed and it comes to be small in the volume thereof; thereby enabling to maintain the discharge volume of molecular beam at a constant. With this, even if consuming the material of thin-film element within the crucible, i.e., the volume of the same is decreased down, gradually, it is possible to maintain the amount of volume of the molecular beam to be discharged at desire, within a controllable range with use of the valve. Thus, up to the time when the remaining of the material of thin-film element within the crucible comes down to be very small, it is always possible to maintain the volume of the molecular beam discharged at a constant value. Also, as was mentioned above, with the control on the volume of molecular beam through adjustment of the heater temperature, it is impossible to obtain an accurate control, due to the time delay, etc., however applying thereof in combination with the adjustment of opening of the valve, it is possible to obtain the accurate control on the volume of molecular beam.

As was explained in the above, according to the present invention, with the molecule beam source for use of accumulating the thin-film and the method for controlling the volume of molecular beam with using thereof, as was mentioned above, it is possible to achieve the control of maintaining the volume of molecular beam discharged at a constant value up to the end, even if the material remaining within the crucible is consumed and thereby comes to be small in the volume thereof, gradually. Furthermore, with applying the adjustment of opening of the valve in combination with the adjustments of the needle valve and the heater temperature, it is possible to control the volume of molecular beam, accurately.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF DRAWINGS

Those and other objects, features and advantages of the present invention will become more readily apparent from the following detailed description when taken in conjunction with the accompanying drawings wherein:

FIG. 1 is a vertical cross-section view for showing an attachment portion of a vacuum chamber, attaching two (2) pieces of molecular beam source cells thereon, for using them at the same time, according to an embodiment of the present invention;

FIG. 2 is a vertical cross-section view for showing one of those molecular beam source cells, according to the same embodiment mentioned above;

FIG. 3 is also a vertical cross-section view for showing the other of those molecular beam source cells, according to the same embodiment mentioned above;

FIGS. 4(a) and 4(b) are enlarged cross-section views for showing an “A” portion and a “B” portion in FIGS. 2 and 3, respectively;

FIG. 5 is a block diagram for showing an example of controls upon valves of the molecular beam source cells and an electric power source of a heater, according to the embodiment mentioned above; and

FIG. 6 is a time diagram for showing an example of controls upon the valves of the molecular beam source cells and the electric power source of the heater, according to the embodiment mentioned above.

DETAILED DESCRIPTION OF THE INVENTION

According to the present invention, the molecular beam source for use in thin-film deposition or accumulation is built up with molecular beam source cells, each applying a valve between a crucible and a vacuum chamber, a detector provided within the vacuum chamber, for detecting an amount or volume of molecular beams discharged, a valve driving means for controlling needle valves of the molecular beam source cells upon basis of a signal from that detector, and a circuit for controlling an electric power for heating the crucible upon basis of a valve position signal.

Hereinafter, embodiments according to the present invention will be fully explained by referring to the attached drawings.

FIG. 1 shows an example of a complex molecular beam source cell, combining a first molecular beam source cell 1 for evaporating a main component, i.e. a thin-film element forming material “a”, such as a material for forming a thin-film on a substrate 51, and a second molecular beam source cell 2 for evaporating a sub-component, i.e., a thin-film element forming material “b”, such as a dopant, etc.

Each of those molecular beam source cells 1 and 2 comprises a material-receiving portion 3 or 4, having a crucible 31 or 41 for receiving the thin-film element forming material “a” or “b” therein and a heater 32 or 42 for sublimating or evaporating the thin-film element forming material “a” or “b”, a valve 33 or 43 to be opened/closed, so as to leak or stop the molecules of the thin-film element forming material “a” or “b”, which is discharged from the material-receiving portion 3 or 4, and a molecule radiation portion 11 or 21, for discharging the molecular beam of the thin-film element forming material “a” or “b” transmitted through the valve 33 or 43, towards the substrate 51, through re-heating it by means of a heater 15 or 24. This molecule radiation portion 11 or 21 is enclosed by a shroud 40, which is cooled with using liquid nitrogen, etc. However, though not shown in the figure, temperatures of the crucibles are measured by a temperature measurement means, respectively, such as, a thermo-couple or the like, for example, a measuring point of which is provided at a bottom portion thereof.

On side of a substrate 51 having a film-forming surface to be formed with a thin film thereof, upon receipt of the molecular beams of the thin-film element forming materials “a” and “b”, which are discharged from those molecular beam source cells 1 and 2, there are provided film-thickness meters 16 and 26, respectively, for detecting the volume of the molecular beams, which are discharged towards that film-forming surface. The film-thickness meter 16 is a detection means for detecting the volume of the molecular beam of the thin-film element forming material “a” discharged from the molecular beam source cell 1, while the film-thickness meter 26 is a detection means for detecting the volume of the molecular beam of the thin-film element forming material “b” discharged from the molecular beam source cell 2.

The molecules of the thin-film element forming materials “a” and “b”, being discharged from molecule discharge openings 14 and 24 of the molecular beam cells 1 and 2, direct onto the substrate 51, which is positioned opposing thereto, to be evaporated thereon. In this instance, a portion of each of the materials directs towards the film-thickness meter 16 or 26, and then the volume can be detected of the molecular beam of the thin-film element forming material “a” or “b”, which is captured by the film-thickness meter 16 or 26. Since there is a certain relationship between the volume of molecular beam detected and the volume of material depositing onto the substrate, therefore the volume of the thin-film element forming material “a” or “b” can be determined, which is deposited on the substrate.

FIG. 2 shows the first molecular beam source cell 1, which sublimates or evaporates the main component, i.e., the thin-film element forming material “a”, thereby irradiating it. The material-receiving portion 3 of this molecular beam source cell 1 has the cylindrical container-like crucible 31, which is made of high heat conduction material of a metal, such as, SUS, etc., and within the crucible 31 is put into the thin-film element forming material “a”.

Surrounding the crucible 31 is provided the heater 32, and further a shroud 39 is provided surrounding an outside thereof, which is cooled through the liquid nitrogen, etc. A heat value of the heater 32 is controlled through the temperature measuring means (not shown in the figure), such as, the thermocouple or the like, which is provided on the crucible 31, and the thin-film element forming material “a” is heated within the crucible 31; therefore, the thin-film element forming material “a” is sublimated or evaporated within the crucible 31, thereby generating the molecules thereof. Also, by stopping heat-generation of the heater 32 while cooling an inside of the crucible 31 with an aid of the shroud 39, the thin-film element forming material “a” is cooled down, and thereby stopping the sublimation or evaporation of the thin-film element forming material.

On side of the crucible 31, from which the molecules of the thin-film element forming material are discharged, is provided the valve 33. This valve 33 is, so-called a needle valve, having a sharp needle 34 and a valve sheet 35 for forming a molecule passage opening, which is closed (or shut off) in the flow passage thereof or narrowed in the cross-section area thereof through insertion of a tip of the needle 34. The needle 34 mentioned above is moved into the direction of a central axis thereof, with an aid of linear movement that is introduced through a bellows 37 from a servomotor 36, which is provided as an actuator.

FIG. 4(a) is an enlarged view of the “A” portion shown in FIG. 2, wherein the tip of the needle 34 is inserted into the a molecule passage opening 38 of the valve sheet 35 through the linear movement thereof mentioned above, or it is separated from the molecule passage opening 38, thereby to open the molecule passage opening 38. This FIG. 4(a) shows the condition where the tip of the needle 34 is inserted into the molecule passage opening 38 of the valve sheet 35, so as to block the molecule passage opening 38; i.e., the condition where the valve 33 is closed or shut off.

As is shown in FIG. 2, at the end of a direction passing through the molecule passage opening of the valve sheet 35, which can be opened/closed by means the valve 33, there is provided the molecule radiation portion 11. This molecule radiation portion 11 has a cylinder-like molecule heater chamber 12, and surrounding this molecule heater chamber 12 is provided the heater 15. Molecules of the thin-film element forming material, leaking from side of the valve 33 mentioned above and reaching to the molecule radiation portion 11 are heated again (i.e., re-heated), up to the desired temperature within this molecule heater chamber 12, and are irradiated from the molecule discharge opening 14 towards the substrate.

On the other hand, FIG. 3 shows the second molecular beam source cell 2, which sublimates or evaporates the sub-component, i.e., the thin-film element forming material “b”, thereby irradiating it. The structures of this second molecular beam source cell 2 are basically same to that of the first molecular beam source cell 1 mentioned above.

Thus, the material-receiving portion 4 of this molecular beam source cell 2 has the cylindrical container-like crucible 41, which is also made of the high heat conduction material of a metal, such as, SUS, etc., and within the crucible 41 is put into the thin-film element forming material “b”.

Surrounding the crucible 41 is provided the heater 42, and further a shroud 49 is provided surrounding an outside thereof, which is cooled through the liquid nitrogen, etc. The structures and functions of the heater 42 and the shroud 49 are completely same to those of the heater 32 and the shroud 39, which are mentioned by referring to FIG. 2.

On side of the crucible 41, from which the molecules of the thin-film element forming material are discharged, is provided the valve 43. This valve 43 is also, so-called a needle valve, having a sharp needle 44 and a valve sheet 45 for forming a molecule passage opening, which is closed (or shut off) in the flow passage thereof or narrowed in the cross-section area thereof through insertion of a tip of the needle 44. The needle 44 mentioned above is moved into the direction of a central axis thereof, with an aid of linear movement that is introduced through a bellows 47 from a servomotor 46, which is provided as an actuator.

FIG. 4(b) is an enlarged view of the “B” portion shown in FIG. 3, wherein the tip of the needle 44 is inserted into the a molecule passage opening 48 of the valve sheet 45 through the linear movement thereof mentioned above, or it is separated from the molecule passage opening 48, thereby to open the molecule passage opening 48. This molecular beam source cell 2 is provided for discharging the sub-component or material, such as, the dopant, etc., and for this reason, it is designed; i.e., an opening diameter of the valve sheet 45 and a taper-angle at the tip of the needle and the maximum opening area of the valve 43, as well, are smaller than those of the molecular beam source cell mentioned above, for discharging the main component or material. Thus, for those, it is possible to conduct the control, accurately, upon the volume of the molecular beam.

As is shown in FIG. 3, at the end of a direction passing through the molecule passage opening of the valve sheet 45, which can be opened/closed by means the valve 43, there is provided the molecule radiation portion 21. This molecule radiation portion 21 has a cylinder-like molecule heater chamber 22, and surrounding this molecule heater chamber 22 is provided the heater 25. Molecules of the thin-film element forming material, leaking from side of the valve 43 mentioned above and reaching to the molecule radiation portion 21 are heated again (i.e., re-heated), up to the desired temperature within this molecule heater chamber 22, and are irradiated from the molecule discharge openings 24 towards the substrate.

According to the present invention, controls are made upon the servomotors 36 and 46, which make adjustment on the opening of the valves 33 and 43 through driving them. At the same time of this, control is also made on an electric power source, which supplies electric power to the heaters 32 and 42 for heating the crucibles 31 and 41. Those controls are conducted with a programming control, through feeding back the volumes of molecular beams discharged from the molecular beam source cells 1 and 2, which are detected by means of the film-thickness meters 16 and 26, and also information relating to the openings of the valves 33 and 43, which are opened by the servomotors 36 and 46.

FIG. 5 is a view for showing a flow sheet of that control system. Basically, the same control system is applied into both of the molecular beam source cells 1 and 2, and then elements of the control system for the molecular beam source cell 2 are indicated by reference numerals put in parenthesis.

As is shown in this FIG. 5, signals are generated from the film-thickness meters 1 and 2, depending upon the volumes of molecular beams discharged from the molecular beam source cells 1 and 2, and those signals are transmitted from processors 17 and 27 to valve controllers 37 and 47 and heater controllers 38 and 48, through molecular beam controllers 18 and 28, respectively.

In an initial period of the operation thereof, the molecular beam controller 18 or 28 transmits an instruction value relating to temperature of the crucible 31 or 41, which is determined in advance, to the heater controller 38 or 48 serving also as an electric power source thereof, and at the same time, calculates out an opening instruction value for the valve, from a preset target value of the volume of molecular beam and the information relating to the present value of the volume of molecular beam, which is transmitted from the film-thickness meter 16 or 26 through the processor 17 or 27, so as to send it to the valve controller 37 or 47.

The valve controller 37 or 47 transmits a driving signal to the servomotor 36 or 46 of the valve 33 or 43, upon basis of the opening instruction value, which is transmitted from the processor 17 or 27, and thereby adjusting the opening of the valve 33 or 43, i.e., a ratio (%) of the cress-section area of flow passage of the valve 33 or 34 to that when it is fully opened. Together with this, it also transmits the opening of the valve 33 or 34 to the molecular beam controller 18 or 28.

As a matter of course, when the volume of molecular beam, which is detected by the film-thickness meter 16 or 26, does not reach to a target thereof, the molecular beam controller 18 or 28 makes adjustment on the valve opening instruction value, in such a manner or direction that the opening of the valve 33 or 34 comes to be large, while when the volume of molecular beam exceeds the target, the valve opening instruction value is adjusted so that the opening of the valve 33 or 34 comes to be small, in the direction thereof.

On the other hand, the heater controller 38 or 48 controls the electric power to be supplied for the heater 32 or 42, so that the temperature of the crucible 31 or 41 measured by the thermocouple, etc., maintains the instruction value, which is provided from the molecular beam controller 18 or 28. Herein, when the present value of the opening of the valve 33 or 43 exceeds an upper limit value thereof, which is determined in advance, the molecular beam controller 18 or 28 transmits the instruction value signal to the heater controller 38 or 48, so as to increases temperature of the crucible 31 or 41. When the temperature of the crucible 31 or 41 increases with this, since the vapor pressure of the thin-film element forming material “a” or “b” within the crucible 31 or 41, then the volume of molecular beam increases even at the same opening of that valve. For this reason, the molecular beam controller 18 or 28 decreases the valve opening instruction value transmitted to the valve controller 37 or 47, trying to maintain the volume of molecular beam to be constant, and therefore, as a result thereof, the present value of opening of the valve 33 or 43 is so controlled that it comes to be lower than the upper limit value. Also, a region of increasing temperature is so controlled that the temperature can rise up to a temperature increasing value, which is determined in advance, or the opening of the valve 33 or 43 is so controlled that it comes to be lower than that, which is determined in advance.

Contrarily, when the present value of opening of the valve 33 or 43 is lower than a lower limit value thereof, which is determined in advance, the molecular beam controller 18 or 28 transmits an instruction value signal to the heater controller 38 or 48, so as to decrease the temperature of the crucible 31 or 41, thereby lowering the temperature of the crucible 31 or 41.

In case when an indicated value of opening of the valve 33 or 43 of the servomotor 36 or 46 lies between the upper limit value and the lower limit value, which are determined in advance, no change is made on the instruction, which is instructed to the heater controller 38 or 48.

FIG. 6 shows the time diagram of the controls mentioned above. When coming small in an amount or volume of the thin-film element forming material “a” or “b” within the crucible 31 or 41, accompanying consumption thereof, then also the value of evaporation of the thin-film element forming material “a” or “b” within the crucible 31 or 41 is decreased, gradually. The molecular beam, which is discharged from the molecule discharge opening 14 or 24 of the molecular beam source cell 1 or 2, is controlled to be constant in the volume thereof, responding to this, by means of the molecular beam controller 18 or 28; therefore, the opening of the valve 33 or 43 comes to be large accompanying with elapsing of the time. And, when the opening of the valve 33 or 43 exceeds the upper limit value “U”, which is determined in advance, a temperature increase instruction is given from the molecular beam controller 18 or 28 to the heater controller 38 or 48, so that the crucible 31 or 41 increases the temperature thereof. Accompanying with this, the volume of the molecular beam, which is detected by the film-thickness meter 16 or 26 per an hour, increases in the tendency thereof. For maintaining the volume of molecular beam, which is discharged from the molecule discharge opening 14 or 24 of the molecular beam source cell 1 or 2, to be constant, responding to this, the servomotor 36 or 46 of the valve 33 or 43 is driven by means of the valve controller 37 or 47; i.e., the opening of the valve 33 or 43 is controlled to be decreased. Thereafter, when the volume of molecular beam, which is detected by the film-thickness meter 16 or 26 per an hour, changes the tendency thereof to increase, then for maintaining the volume of molecular beam, which is discharged from the molecule discharge opening 14 or 24 of the molecular beam source cell 1 or 2, to be constant, responding to this, the opening of the valve 33 or 43 is controlled to be large by means of the valve controller 37 or 47, again. In this manner, the volume of molecular beam, which is detected by the film-thickness meter 16 or 26 per an hour, is controlled to be constant, i.e., maintaining a stable value thereof.

However, in case when increasing the temperature of the crucible 31 or 41, in a step-like manner by a unit or width of temperature increase, which is determined in advance, that unit or width of temperature increase must be determined in advance, through experimentation and/or calculation, at such temperature that the volume of molecular beam, which is detected by the film-thickness meter 16 or 26 per an hour, changes the tendency thereof to decrease under the condition where the opening of the valve 33 or 43 does not reach to the lower limit value “L”, and then there is a necessity of increasing the valve opening thereafter.

Although the embodiment mentioned above shows the example of obtaining the film forming through discharging of the molecular beams from the two (2) pieces of the molecular beam source cells towards the substrate 51, however it is of course that the present invention can be also applied into a case where the film forming is obtained through discharging of the molecular beam from a single molecular beam source cell towards the substrate 51, or into a case where the film forming is obtained through discharging of the molecular beams from three (3) pieces or more of the molecular beam source cells towards the substrate 51, and so on.

The present invention may be embodied in other specific forms without departing from the spirit or essential feature or characteristics thereof. The present embodiment( s) is/are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the forgoing description and range of equivalency of the claims are therefore to be embraces therein. 

1. A molecule beam source for use of accumulating a thin-film, for evaporating a material of thin-film element, comprising: a crucible for heating the material of thin-film element; a heater for heating said crucible; a molecule discharge passage for discharging molecules of the material of thin-film element generated within said crucible towards a film-forming surface; a vacuum container having hermetical sealed structure, for receiving said crucible, said heater and said molecule discharge passage therein; a valve for adjusting a volume of molecular beam discharged, being positioned on way of said molecule discharge passage; a detection means for detecting the volume of the molecular beam discharged towards said film-forming surface; a controller means for adjusting an opening of a valve by a valve driving means through feeding back information relating to the volume of the molecular beam detected by said detection means; a heating electric power source for supplying electric power for use of heating said heater; and a control means for adjusting the electric power to be supplied to said heating electric power source depending on said information relating to the volume of the molecular beam and valve opening information.
 2. A method for controlling a volume of molecular beam, within a molecule beam source for use of accumulating a thin-film, for evaporating a material of thin-film element, comprising: a crucible for heating the material of thin-film element; a heater for heating said crucible; a molecule discharge passage for discharging molecules of the material of thin-film element generated within said crucible towards a film-forming surface; a vacuum container having hermetical sealed structure, for receiving said crucible, said heater and said molecule discharge passage therein; a valve for adjusting a volume of molecular beam discharged, being positioned on way of said molecule discharge passage; a detection means for detecting the volume of the molecular beam discharged towards said film-forming surface; a controller means for adjusting an opening of a valve by a valve driving means through feeding back information relating to the volume of the molecular beam detected by said detection means; a heating electric power source for supplying electric power for use of heating said heater; and a control means for adjusting the electric power to be supplied to said heating electric power source depending on said information relating to the volume of the molecular beam and valve opening information, comprising the following steps of: adjusting the electric power to the electric power source for heating said crucible if the valve opening necessary for obtaining a predetermined volume of molecular beam is equal to a predetermined reference value or larger than that, when evaporating an organic material upon a substrate, continuously; and thereby controlling the valve opening to fall within a range. 